Apparatus and methods for dispensing foamable products

ABSTRACT

New and improved foam cushions for packaging purposes of the type including a cushion envelope partially filled with an expandable cushioning foam material are provided. The cushion envelope includes a foam-receiving cavity and is defined by a unitary web of material folded over itself to provide a folded side. An intermittent labyrinth side seam is provided along the side opposite the folded side and transverse top and bottom seams are provided to complete formation of the cushion envelope. A cushioning foam is disposed in the foam-receiving cavity. A method for making the foam cushions and an automated apparatus for making a continuous supply of the packaging cushions are also described.

The present invention relates generally to apparatus and methods forforming a plurality of individual foam-filled bags used for protectivecushioning purposes. More particularly, the invention relates to methodsand apparatus whereby a single web of flexible sheet material isintermittently advanced along a given axis, wherein side and end seamsare formed therein to create a partial envelope with an open upstreamside through which a charge of foamable material is deposited into thedownstream portion of the partial envelope, following which the envelopeis divided by the formation of a pair of end seams into one portioncomprising a formed and filled bag and another portion wherein theupstream portion has become the downstream portion and a new upstreamportion has been formed from a following increment of the flexible sheetmaterial. At least one side seam is a labyrinth side seam which confinesthe foamable materials but permits the bag to be vented duringintroduction and subsequent expansion of the foam.

While the invention is capable of other uses, it is advantageously usedin the protective packaging industry to form individual bags which areused in sets of two or more, together with an exterior container such asa corrugated paper box, to provide protective cushioning for delicateobjects during shipment.

In the packaging industry, there has been a need for improved methodsand apparatus for manufacturing cushioning bags used in the packagingindustry. It has for years been conventional in the packaging industryto protect fragile articles being shipped by providing a corrugatedcardboard box, filling a part of the box with foamable ingredients froma dispenser, placing a plastic sheet over the rising upper surface ofthe foam, then placing the object to be protected in the box, coveringthe object with another sheet of plastic material and then adding anadditional charge of foam over the plastic sheet before closing the topedges of the box.

This packaging method, and the articles produced thereby, are known tobe advantageous in offering a certain degree of flexibility andexcellent protection in use for fragile articles. However, thispackaging method does require significant skill on the part of theoperator, and sometimes creates the risk that the foam will not beaccurately directed or its "shot size" may be misjudged.

Moreover, it can become tedious and nerve-wracking for the operators whomay not have accurate control over the amount of ingredients dispensed,or other process variables. Moreover, this method is susceptible tovariations in timing, i.e., the time wherein the protective sheet isplaced down may vary among individual operators and create a certainamount of unreliability.

In addition, protecting the article relies on proper placing of thecover sheet and this may be done somewhat erratically. If the packagingprocess is carried out by a single operator, several manipulative stepsare required. If the process is carried out by two people, onemanipulating the sheets and the other discharging the foam, the processcan become relatively labor-intensive.

Accordingly, there has been a need in the industry to develop packagingmethods and apparatus which achieve the ability to provide closelyconfining, highly effective cushioning for shipped articles withoutcertain of the drawbacks of the prior art. In this connection, it hasbeen proposed to use individual bags of expanding foam as the cushioningmaterial, with the thought of being able to control closely the shotsize and hence volume of the foaming material, controlling thesevariables in relation to the box portion of the package. Where thecontents are confined to a bag or other container, the need for carefulcovering of the expanding foam front may be obviated. This approach hasproved successful but, because of certain of its own problems, iscapable of further improvement.

Besides the foregoing, in the past, some of the apparatus for formingand filling bags of foaming material have been unduly complex andexpensive, or have required relatively skilled labor. In other cases,machines have required careful control of the seaming processes or thefilling operation. In some machines, regulation of shot size wasdifficult, or the process by which the individual bags were formedrequired relatively complex or unreliable sheet guiding and feedingapparatus. In some machines, the formation of the top seam with thevents necessary to permit internal foam expansion rendered separation ofthe filled bags problematical and disadvantageous. Other bag-formingmachines using foam-filling techniques were more or less effective, butstill capable of significant improvement.

In the preferred form, the apparatus of the invention uses a flexibleexterior sheet material, such as a thin sheet of polyethylene film toform the bag exterior; reactive ingredients are mixed and dispensedwithin the bag being formed in a manner to be described herein.Preferably, but not necessarily, the reactants form a flexible urethanefoam of very low density, such as about 0.4 lb./cu. ft. The low densityurethane foam is made from a polymeric isocyanate and one or morehydroxyl-rich resins; the exact formulations do not form a part of thepresent invention but are known to those skilled in the art.Formulations may be varied to suit the intended end use of the product,i.e., rise time, density, degree of cross-linking, type of blowingagent, etc.

While the invention is not limited to the particular embodimentsdescribed herein, several advantages are realized by the novel featuresof the preferred form of invention. One novel feature is the use of asingle web of folded-over material to form the envelopes, and ultimatelythe bags, which are filled with the cushioning material. This methodeliminates the need for forming a separate second side seam in thefinished product.

Another preferred feature of the invention is the formation of alabyrinth type side seam in the envelopes and bags of the invention. By"labyrinth" as used herein, and in the claims, is meant a discontinuousside seam of the type which will provide venting of gas and vapormaterials during bag formation and subsequent expansion but which willstill provide an obstacle to the flow of expanding, curing urethane orsimilar foam. According to the invention, various forms of seams may beformed so as to provide a tortuous or indirect path of narrowcross-section which readily permits the escape of gas or vapors, butwhich, because of the adhesive character and the continually increasingviscosity of the foam as it cures, serves as an effective obstacle tothe passage of the expanding foam.

Hence, the apparatus of the invention may use the folded-over web tocreate a side seam on one side of the bag and seal the top and bottomends (or leading and trailing edges) of the bag completely without riskof foam leakage through the labyrinth side seam. This is especiallyadvantageous in relation to the prior art practices of formingintermittent seams on the top and bottom edges of the product, as willappear.

The intermittent, labyrinth type side seam enables better control overend seam formation to be achieved, and this in turn aids in separatingindividual bags from each other as they are produced in sequence.

Another aspect of the invention is the arrangement of rollers which fromthe intermittent side seam in such a way that one or both rollers may berapidly changed when it is desired to alter the labyrinth pattern.

In the preferred form, the method of the apparatus involves forming whatis herein termed an elongated partial envelope, i.e., a folded-over webwith a leading edge seam and a partial side seam forming its downstreamportion, and opposed facing sheets of material with at least one openside forming the upstream portion of the envelope. Because in thepreferred form of apparatus, the web of material is advanced downwardlyas the bags are formed and filled, "lower" and "downstream" aresometimes used interchangeably. However, the invention is not strictlyconfined to vertical web movement. The open side of the envelope permitsthe dispensing unit to extend through the open side seam.

According to the inventive method, the liquid foamable materials passfrom the dispenser in the upper portion of the envelope to the lower orbottom portion of the envelope where they are confined by the bottom orleading edge seam, preferably as it is traveling downwardly. As the webcontinues to travel downwardly and a charge of material passes into thelower portion of the envelope, the side seam continues to be formedafter the materials cease to be dispensed.

After a predetermined increment of travel is reached, the advancementceases transiently and a double end seam separated by a line of weaknessis formed in the web, using a retractable seal bar arrangement. Thisforms the top or trailing edge seam on the lower bag and forms theleading edge or bottom seam of the next or upper envelope. Uponresumption of web advancement, the downstream, filled bag may beseparated while the foam is still expanding and used in a manner whichis known to those skilled in the art but which will be referred toherein. In the meantime, when advancement of the web resumes, the sideseam on the envelope continues to be formed, dispensing occurs and foamexpansion begins and then ceases while an additional length of side seamis formed and the end seam forming sequence is repeated. At the sametime, other increments of web material are advanced to form newupstream, open-sided portions of the partial envelopes. Thus, thedispensing action fills the elongated envelope, which is subdivided soas to form a bag as a new upper envelope portion is formed. Thedispensing occurs after each end seam formation and hence the liquidtravels from the dispensing head located above the seam-forming bars tothe seam which remains below the seam-forming bars. In the preferredform, means are provided for guiding the web so that a full bag orenvelope width is maintained, bearing in mind the total width of thefolded over web. Various auxiliary functions are provided in theapparatus of the invention, and their identity and function will appearas the description proceeds.

In view of the above-cited and other drawbacks of some prior art bagforming and filling methods and apparatus, it is an object of thepresent invention to provide an improved apparatus and method forforming and filling cushioning bags. The present inventive apparatus andmethods overcome some or all of these drawbacks.

Another object of the invention is to provide a forming and fillingapparatus which may be manufactured at low cost and which is simple andreliable in operation.

Another object is to provide a bag forming and filling machine whichembodies a novel operating sequence.

A further object of the invention is to provide an apparatus forproducing a series of bags filled with cushioning foam, which apparatusembodies a novel method or operating sequence in use.

A further object of the invention is to provide a method of forming andfilling bags with cushioning foam, with the preferred method includingthe steps of utilizing a single, folded-over web of material with itsopen side providing access for a foam dispensing head, and whichincludes further steps of forming an envelope from this web, dispensingfoamable liquid reactants into a downstream portion of the envelope asit is being advanced and formed, and then forming end seams to subdividethe envelope into upstream and downstream portions, with the downstreamportion forming a filled bag and the upstream portion advancing andbringing an additional increment of film material for subsequent fillingand subdivision.

Another object of the invention is to provide an apparatus whichincludes means for guiding a folded-over web of film around a dispensinghead and forming a labyrinth type, intermittent side seam on the openside of the web of material to provide a bag with one or more ventedside seams preventing escape of foam-cushioning material.

A further object of the invention is to provide an apparatus which inuse forms labyrinth type, intermittent side seams in cushioning bags,thereby permitting the bag to be vented of gases or vapors and yetretain curing foamable fluids of increasing viscosity.

A still further object of the invention is to provide a bag-formingmachine which, as a part of its operating sequence, provides an envelopewith an open upper portion which may be filled and in which the envelopemay be subsequently subdivided, into a filled bag which may be removedfrom the remainder of the envelope.

Yet another object of the invention is to provide an apparatus whichincludes a novel form of roller apparatus for creating a labyrinth typeintermittent side seam.

A still further object of the invention is to provide a bag-forming andfilling machine having an operating sequence which is readily adaptableto making bags of various widths and lengths in use, and filling themwith different amounts of foamable material.

Another object of the invention is to provide a bag-forming and fillingmachine wherein an operator may vary the bag length by simplemanipulation of length controls.

A still further object of the invention is to provide an apparatus andmethod which provides high quality bags for use in the packagingindustry at low cost and without requiring skilled operator labor.

The foregoing and other objects and advantages of the invention areachieved in pratice by providing a machine which includes means forreceiving a supply of a flexible, bag-forming material in web form, forguiding the web of material past a dispenser unit so as to provide anopen side edge portion through which the dispenser may extend, forintermittently advancing a portion of the web to form a partial,elongated envelope, filling a part of the envelope with a charge offoamable liquid, and subdividing the filled part of the envelope fromthe unfilled part to create a filled bag by forming a seam betweenfilled and unfilled parts of the envelope.

The invention also achieves its objects by providing a method ofintermittently advancing a web of material and forming envelopes fromthe material, filling parts of the envelopes with a foamable materialand then subdividing the envelope into a leading, filled bag portion anda trailing, unfilled, open-sided portion, and thereafter advancing theopen side portion and seaming its open side to form a completed,bag-forming portion of a following envelope.

The manner in which the foregoing and other objects and advantages areachieved in practice will become more clearly apparent when reference ismade to the following detailed description of the preferred embodimentsof the invention set forth by way of example and shown in theaccompanying drawings, wherein like reference numbers indicatecorresponding parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one form of the apparatus formanufacturing foam-filled pillows or cushions according to theinvention, with such apparatus being shown to include a frame unit,means for positioning a supply of flexible bag-forming material in webform and for advancing and guiding the web material past a bag formingand filling station which includes a dispensing head, a pair of seamingrollers, and means for heat sealing adjacent web margins to form thetrailing and leading edge seams respectively on a completely formed andfilled bag and on a partial envelope from which a filled bag will beformed;

FIG. 2 is an enlarged fragmentary front elevational view, with portionsbroken away, showing certain elements of the envelope and bag formingand filling apparatus of FIG. 1 in greater detail;

FIG. 3 is a top plan view of the apparatus of FIG. 1, showing otheraspects of the forming and filling station, and also showing thedispenser and certain details of the rollers for forming the labyrinthseal on the bag margin;

FIG. 4 is a greatly enlarged fragmentary front elevational view of aportion of a bag incorporating one form of labyrinth seal of theinvention;

FIG. 5 is a vertical sectional view, taken along line 5--5 of FIG. 4 ona further enlarged scale, and showing the foam expanding within thelabyrinth seal forming a part of the bag of FIG. 4;

FIG. 6 is a vertical sectional view, taken along lines 6--6 of FIG. 3,and showing the manner of filling the lower portion of the elongatedenvelope from which a filled bag will be formed;

FIG. 7 is a view similar to that of FIG. 6, showing a leading bagalready formed, filled, and being separated from the envelope and theformation of a new partial envelope with a closed leading edge seam anda partially completed side seam;

FIG. 8 is a diagrammatic view illustrating certain steps of the methodof the invention and showing a folded-over web of flexible material inrelation to the dispenser unit of the invention, before the envelope isformed;

FIG. 9 is a diagrammatic view similar to that of FIG. 8, but showing theenvelope partially formed by the creation of a side seam where theopposed free margins of the web are bonded together by a labyrinth sideseam;

FIG. 10 is a view similar to that of FIGS. 8 and 9 and showing in adiagrammatic way the formation of the transverse top and bottom seamswhich begin to define a foam-receiving pocket in the web material andfurther showing a charge of foamable material beginning to be depositedinto the downstream portion of the envelope which now includes leadingedge seams and side seams;

FIG. 11 is a view similar to that of FIG. 10, showing foam depositionbeing discontinued and completion of the side seam past its point ofintersection with the end seam to be formed;

FIG. 12 is a view similar to FIGS. 8-10, showing a finished and filledbag being separated from a following bag, an intermediate bag which isfilled and seamed, and wherein the foam is continuing to expand furtherupstream, and an envelope beginning to be formed from a following oruppermost increment of web material from which a bag is about to beformed by seaming portions of the opposed webs together to form endseams;

FIG. 13 is a diagrammatic view of the manner of packaging a fragileproduct using a shipping box or like container and foam-filled bags madeaccording to the invention;

FIGS. 14-16 are diagrammatic views similar to those of FIG. 13 andshowing respectively the placing of an object atop a still-expanding,foam-filled bag, covering the object with a second, similar bag andclosing the box to confine the article and complete the customary bagexpansion while the bags and the object are confined within the box;

FIG. 17 is an enlarged vertical sectional view, taken along lines 17--17of FIG. 3 and showing certain details of one form of seal bar used toform the transverse end seams and the lines of weakness for separatingthe bags from each other;

FIGS. 18-19 are views similar to FIG. 17, showing the operation of theseal bars of FIG. 17;

FIG. 20 is an enlarged fragmentary view of the seal bars of FIGS. 17-19,taken along lines 20-20 of FIG. 2;

FIG. 21 is a vertical sectional view, on a greatly enlarged scale,showing details of one form of seaming roller of the invention used toform a labyrinth seal;

FIG. 22 is an elevational view of the roller of FIG. 21; and,

FIGS. 23-25 are developed or projected views of different profiles ofseaming rollers useful to form the labyrinth side seal on bags madeaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

While it is understood that the invention may be embodied in differentforms of apparatus, and that a method of the invention may be practicedby machines other than the one described herein in detail, for purposesof illustration, reference will be made to a presently preferred form ofapparatus for forming and filling flexible bags.

Referring now to the drawings in greater detail, a bag forming andfilling apparatus generally designated 10 is shown to embody theinvention. The forming and filling apparatus includes a number ofsubassemblies, some of which may be described in generally functionalterms before reference is made to the details of their construction.

These subassemblies include a machine frame generally designated 12,means generally designated 14 for positioning a roll or other supply ofmaterial generally designated 16 in continuous web form and from which aplurality of individual, foam-filled bags generally designated 18 (FIGS.12 and 13-16) may be formed. The apparatus 10 also includes a bagforming and filling head generally designated 22 and which includesmeans for performing other principal operations incident to bag formingand filling. These include means generally designated 23 for guiding aweb 24 of material from which the individual bags 18 are formed over adispenser unit generally designated 26, for depositing individualcharges of foamable reactants into the being-formed bags pursuant to the"instructions" furnished from a control panel 28. In addition, the head22 includes means generally designated 30 in the form of a roller pairfor forming a side seam on the bag and means generally designated 32 forforming transverse seams on the ends of the bags being formed and filledfrom time to time during machine operation.

Additionally, FIG. 1 shows that means in the form of tanks 34, 36 areprovided for storing the reactants from which the foamable compositionsare mixed, and that conduit means in the form of tubes or hoses 38 forsupplying these liquid reactants to the dispenser 26 are also provided.

Each of the foregoing principal elements or subassemblies in turncomprises a number of individual elements, some or all of which aredescribed in detail herein. Other principal subassemblies include adrive motor assembly generally designated 40 (FIGS. 2-3), a drive trainsystem generally designated 42, a control unit generally designated 44for synchronizing the web feed and ingredient dispensing functions, adispensing head cleaner unit generally designated 48, left and righthand drive roller pairs 50, 52, the right hand pair of which ispreferably a roller pair for intermittent labyrinth tape side seam toseal the free margins of the web to each other.

Referring again to FIGS. 1-3, the machine frame 12 is shown to include apair of substantially identical left and right hand vertical posts 54,56, a top cross member 58 supporting the forming and filling head 22.The frame also includes a lower cross member 59, a pair of horizontallegs 60, 62 terminating in four identical foot or pedestal units eachdesignated 64. In the preferred form, a pair of support brackets 66 (oneonly shown in FIG. 1) extend upwardly from the rear of the frame legs60, 62 and are positioned by a transverse frame unit 68 and a rolleraxle 70. The web 24 extends upwardly from a roll of film 71 supported onthe axle 70 at the rear of the machine.

Referring now to other constructional details of the forming and fillinghead 22, the head 22 includes a frame generally designated 72 and shownto include side members 74, 76, a rear cross brace 78 and a center crossbrace 80 (FIG. 3). In addition, the head 22 serves to position web topguide means in the form of an upper cross bar 82 extending betweenbrackets 84, 86 secured at or near the top of vertical struts 88, 90.The right hand strut 90 also includes a bracket 92 for positioning anintermediate cross bar 94 which in turn carries a bracket 96 forsupporting a sheet edge positioner generally designated 98. An endportion 100 which is generally C-shaped in front elevation serves as theedge guide for the positioner 98; this positioner engages the foldedover web to position its left margin.

Referring in particular to FIG. 2, it will be noted that the strut 90also includes an adjustable dispenser support bracket 102 to which adispenser head generally designated 104 is securely fixed. At the end ofthe bracket 104 is a dispenser control unit 106 controlled by lines 108,110 making desired connections to the control unit 44. The lower portionof the dispenser 26 includes a mixing chamber 112, an outlet nozzle 114and inlets for the pair of substantially identical ends 116 on hoses 38.The end portion 118 of a nozzle rinsing assembly is also shown.

From the foregoing, and referring in particular again to FIG. 2, it willbe noted that the web of sheet material is positioned in face-to-face,doubled over relation so as to form a folded-over edge generallydesignated 120 on its left side and to provide overlying, alignedmargins 122, 124 (FIGS. 8-12) which are spaced apart in the front torear sense so as to permit entry of the dispenser head.

Referring now to FIG. 2 and 3, the operation of the motor and drivetrain systems 40, 42 for advancing the web will be described. Principalelements of the drive mechanism include a holddown bracket 126 for themotor 40, a motor control unit 128, a drive shaft 130, a drive sprocket132 for actuating a toothed belt 134 which is trained over and drives adriven sprocket unit 136. A shroud 138 customarily covers the drive beltand sprocket system.

The driven sprocket 136 is keyed to and causes rotation of a main rollerdrive shaft 140, and a gear set of a conventional kind (not shown indetail) disposed within a drive cover housing 142. In use, the meshinggears cause the driven or countershaft 144 to rotate at the same angularvelocity as the main shaft 140, whereby the driving and driven rollers146, 148 of the left hand roller pair 50 rotate at the same peripheralspeed and serve to pinch between them and advance a portion of the web.Seaming rollers 150, 152 comprising the right hand side roller pair 52are likewise keyed to the same respective shafts 140, 144 and rotatewith the same peripheral velocity. In use, therefore, assuming that asignal from the feed control unit 44 is sent to the motor control 128and the motor 126 is energized, the combination of drive shaft, varioussprockets and belts will cause both roller pairs 50, 52 to advance theweb in increments of length determined by the signal fed to the motordrive control 128. Likewise, the feed control unit 44 also instructs thedispenser 26 when a charge of material is to be deposited, as by sendingappropriate signals through the leads 108, 110. As will appear, thefoaming ingredients are customarily deposited during a part, but not allof, the time the web is being advanced.

Referring now to a desirable, but not necessary, safety feature of theinvention, a deposit override control assembly generally designated 154is provided, and this unit is shown to include a rotor 156 or the likewith a plurality of magnetic bars spaced about the circumferencethereof, a Hall effect or like pickup device 158, and a conductive lead160, having one end attached to the pickup 158 and the other to the feedcontrol unit 44. As implied by the name, this safety device providesfeed to an "and" gate within the feed control unit 44 whereby when adeposit of foamable materials is called for by the operator, the Halleffect pickup device 158 must detect rotary motion in the driven rollerand pass an enabling signal to the control 44 as a condition toenergizing the dispenser unit 26. In other words, the foam will not bedeposited unless the web is advancing, at least insofar as this can beindicated by rotation of the countershaft 144.

Another principal feature of the apparatus is the means 32 for formingthe end seam on the web and providing areas of weakness for separationof adjacent bags.

Referring to FIGS. 2, 3, and 17-20, the seam-forming means is shown tocomprise a pair of horizontally spaced apart, front and rear heatsealing bars generally designated 162, 164. As shown in FIG. 20, theleading or front bar 162 includes a pin 166 disposes at its end portionand extending through a clevis 168 on the end of an operating rod 170;the other end of the rod 170 cooperates with a piston (not shown) lyingwithin a piston and cylinder assembly 172 to cause reciprocation of thebar 162 in the directions of the arrows. The inwardly directed facesgenerally designated 174 of the bar 162 includes a heat seal unit whichwill be described in detail. As is further shown in FIG. 20, the innerbar 164 also includes a pin and clevis arrangement 176, an operating rod178 and a piston and cylinder assembly 180. The edge portion 182includes heat sealing elements as will be described.

A heat seal controller assembly generally designated 184 includescontrols of a conventional kind and is adapted to send pneumatic powerthrough lines 186 to the piston and cylinder assemblies. In an alternateform, these may be actuated electrically, as by solenoids orhydraulically, if indicated.

Referring now to FIGS. 17-19, it will be noted that in the preferredform, one bar, such as the seal bar 162 includes on its face portion 174upper and lower heated surfaces 188, 190 separated by a wire 192; arubber buffer unit 194 is disposed above the bar 162 with its faceparallel to the inner face of the seal bar 162. Opposed facing sheets"S" of the material for forming the heat seal are schematically shown asextending downwardly between the bars. The right hand side (FIG. 17) orinner heat seal bar 164 is shown to include a surface pad 196 formingthe part of its surface which opposes the surfaces 188, 190, and thewire 192; this pad cooperates with its counterparts on the other bar toretain and form the heat seal. A positioner element 198 is disposed atopthe bar 164 and cooperates with the rubber buffer 194 such that the noseportion 200 on the positioner element 198 serves to preposition or holdthe sheets "S" together.

FIG. 18 shows the sheets entrapped between the bars 162, 164 and showsthat the heated wire sealing element 192, which projects beyond thefaces of the other heat seal surfaces 188, 190 is creating a reducedthickness section of the film and hence a line of weakness 202 (FIG. 19)in the film between the opposed heat seal bands or margins 204, 206.FIG. 19 shows the areas 202, 204, 206 just referred to after the barshave been separated from each other.

Referring now to another important feature of the invention, the righthand side or seaming roller pairs 52, and in particular the constructionof the outer or heated labyrinth seaming roller 150 is shown in detailin FIGS. 21 and 22. Here, it is shown that the drive shaft 140 extendsthrough and is press fit into a layer 208 of insulation ensuring thatthe roller 150 will rotate with the shaft. The roller assembly 150includes an inner, electrically conductive cylindrical core unit 210spaced by a cylinder 212 of electrical insulation from an outer cylinder214 which is also electrically conductive.

The outermost surface of the seaming roller 150 is formed from anelectrically insulating, smooth, non-adherent layer 216 of a materialsuch as a silicone rubber and includes an electrically conductiveresistance tape 218 laid thereover. One end 220 of the tape (FIG. 22)218 is in contact with the electrically conductive flange 222 of theouter cylinder 214. The other end 224 of the tape 218 is in electricalcontact with a pin 226 which extends into electrical contact with theinner conductive cylinder 210. A radial flange 228 of the inner cylinder210 is also electrically conductive, and consequently, electricalcurrent may be fed in the use of the device from a lead 230, throughbrushes 232 positioned by springs 234 urging the brushes against theflange 222 of the outer cylinder 214. The current then passes throughthe entire length of the tape and thence through the pin 226 into theinner cylinder 210 where electrical contact is made through brushes 236,providing a return current path through the other spring set 238 andreturn conductor 240.

According to the invention, and referring now to FIGS. 23-25, it isshown that the outer surface 216 of the roller 150 in a projected viewappears to have the electrically conductive tape 218 running diagonallythereacross. As shown in FIGS. 24 and 25, for example, the surfaces216a, 216b may have different forms of conductive tape 218a, 218b ontheir surfaces to provide a different labyrinth pattern.

For example, the form of tape shown in FIG. 23 will form a series ofdiagonal heat seal bands on the margin of the being-formed bag. Themargins will have one edge beginning where the other ends, and have adiagonally extending offset pattern.

The form of seal shown in FIG. 24 provides an overlap somewhat asillustrated in FIG. 4; here, diagonally extending heat sealed areas 250,252 are formed in the margin 254 of the bag 18. Other patterns such asthe pattern shown in FIG. 25 may be desirable for use, depending on theintended application. In this connection, reference is made again toFIGS. 4 and 5 where the operation of the seal is shown.

Here, a plurality of passages 256, 256a, 256b, 256c, for example areshown. As the foam begins to move into the passages 256, 256a, forexample, a relatively long path of relatively narrow cross section isprovided. As the foam expands and passes through this path under theinfluence of gravity and its own expansive tendencies, its viscosity andadhesion are gradually increasing, and it requires energy to fill theentire passage. As its viscosity increases and its adhesion to the filmcontinues to increase, resistance to flow increases and alternate,upstream paths such as the paths 256b, 256c begin to fill. Thiscontinues with the foam extending into, but not passing through thepassages, whose side seam angle and hence whose length and cross sectionis determined after suitable experimentation. The open passages permithot air and residual propellant gas or vapor to pass from the interiorof the bag to the exterior, but because of the labyrinth effect, preventthe solidifying foam from leaking from the side of the bag.

Referring now to FIGS. 8-12, the method of the invention is shown in arelatively simple, schematic form. Referring to FIG. 8, the web 24 ofmaterial is shown being advanced along a horizontal axis and then movingalong a vertical movement path. In the form shown, the web 24 is foldedover upon itself so as to form opposed sheets 260, 262 folded about acommon closed edge 120. Opposed margins 122, 124 then overlie each otheras the web is advanced downwardly. These margins 122, 124 are spacedapart from each other to permit the dispenser unit 26 to extendtherebetween. The dispenser 26 therefore has its nozzle portion 114enclosed between the two facing sheets. This illustrates the manner offeeding the web of flexible material before the first part of envelopeformation takes place.

FIG. 9 shows the next step in forming a partial envelope generallydesignated "E". This is carried out by creating a side seam generallydesignated 125 and comprising a plurality of the labyrinth style heatseals such as the heat seal strips 256 shown in FIG. 4. FIG. 9 thusshows what may be described as a partial envelope having the one closedside seam 120, and a partially open upstream side seam formed by theportions 125, 122, 124 respectively.

FIG. 10 shows the next step in the process, that is, the step of formingtransverse, closely spaced apart seams 204, 206, separated by a line ofweakness 202 therebetween. Referring to FIG. 10, it will be understoodthat, when the process of the invention is initially begun, only one endseam is required. Thereafter, the end seams are formed in pairs becausethe seam-forming operation comprises completing the formation of aleading bag and performing an intermediate step in the formation of theenvelope which will become the following bag. As soon as the transverseseam 204 has been formed by reciprocation of the heat seaming bars 162,164 and maintaining them together for a suitable dwell time, the bottomseam of the envelope is formed and deposition of the foamableingredients, such as the charge of materials "F" (FIG. 11) begins.

Referring again to FIG. 11, it will be noted that the length of the sideseam 125 is increasing, inasmuch as the side seaming operation continueswhile the web is being advanced through another increment of length. Thepreviously formed seamed area comprising the seams 204, 206 and the lineof weakness 202 advances downwardly. After a few seconds, a full chargeof foamable ingredients has been deposited and further depositionceases. The web is normally advanced for a brief time thereafter andadditional side seam 125 continues to be formed. Thereupon, theadvancing mechanism is transiently disengaged and a second set of seams204a, 206a is formed in the web. This fininshes the creation of a filledbag 18, and the bag may be separated along the line of weakness 202, asits predecessor has been in the manner illustrated in FIG. 12. FIG. 12also shows that a new side seam is beginning to be formed and thatduring this entire operation, additional increments of the web 24 havebeen advanced from the supply (not shown) so that the continuous processof envelope formation and filling, and bag completion and separation maybe carried out.

In the form of invention described, and as presently preferred, thefolded-over single web of material provides advantages in use for thereason that only a single side seam is required to be formed. As shownin FIG. 1, the side seam guide unit 100 may be positioned so as to liefarther to the left or right if it is desired to make a bag of differentwidth. The roller pair 50 which serves to advance the folded-over edgeof the sheet material may be moved to an appropriate position; this isthe only change required to make a narrower or wider bag.

Referring now to the matter of bag length, it is possible to create bagsof any length by simply programming the controller 42. A suitable meansof doing this may be programming a microprocessor (not shown) of a typeknown to those skilled in the art, for actuating the drive motor for adifferent time interval. The programmer may be set to advance the bagcontinuously until commanded to stop, or may have available a number ofpreset advance durations, or both. Preferably, the duration may beadjusted and programmed such that a choice of three or four typicalincrements of length, and continuous advancement, will be available.Similarly, the same type of control may be programmed for use inselecting from preset durations of ingredient dispensing, or the programmay permit manual, control over the duration of product deposition.Preferably, a manual mode of control is available for each operation sothat, for example, a bag length of 24 inches might correlate with adispensing time of 2 seconds; a bag length of 36 inches with 3 seconds,etc. The manual mode may be selected to cooperate with a predeterminedor continuous length of web advancement.

Another feature of the invention is the provision of a nozzle rinsingapparatus shown as 118. Here, a small pneumatic accummulator may be usedin conjunction with a supply (not shown) of solvent. After completion ofeach dispensing cycle, a short burst of solvent is directed by an airstream across the face of the nozzle 114. The material dislodged isblown towards the closed side of the being-formed bag and remains insidethe bag interior.

In the preferred form of apparatus, the isocyanate and resin componentsreceived in the tanks 34, 36 respectively may be fed through the hoses38 by a separately supplied, nitrogen overpressure system of a kindknown to those skilled in the art. This system obviates the need forpumps or the like and has proved successful in other urethane-dispensingoperations. Other auxilliary functions may be provided in the machine,such as initiation of the operation by push buttons on the console 28 orthe like. As shown, the various guide arrangements are in the form ofadjustable clamps which may be made in a suitable manner depending onthe size of the web or other application variables.

In the preferred manner of use, the operator obtains a plurality ofboxes such as those shown in FIGS. 13-16, and as the bags 18 are filled,and detached from the following bag in the formation and fillingsequence, the bags are placed in the boxes "B" (FIG. 18). Then a package"P" is inserted as shown in FIG. 14. During this time, the foam withinthe bag has expanded significantly but is still capable of and is infact undergoing, further expansion. The package "P" then rests upon theupper surface of the further expanding bag 18 and as expansioncontinues, another bag 18a (FIG. 15) is placed over the package "P" andthe flaps "F" of the box "B" are moved to a closed and sealed positionas shown in FIG. 16. The flaps are then held in this position as bysecuring with tape or otherwise until foam formation is complete. Thisensures that the package "P" will be closely surrounded and supported incushioning relation to the box "B".

FIGS. 6 and 7 may be taken in connection with the description of FIGS.8-12 and illustrate the dispenser 26 in dispensing a charge of foam intothe bag being formed from the web of sheet material. The positions ofthe sealing bars 162, 164 are shown with portions of their actuatormechanisms. A vertical dispensing arrangement is shown and is apreferred form of practicing the invention. It is possible that thedispensing may occur in a horizontal plane if the foam can be propelleda suitable distance. However, the use of gravity to secure foamdeposition past the planes respectively of the side seaming roller andthe sealing bars into the area therebeneath is the preferred form ofinsuring that the foam is confined during foaming and yet there iscontinuity of the web until the complete bag has been formed prior tointentional separation.

It will thus be seen that the present invention provides a lost cost,reliable method and apparatus for forming and filling bags of flexiblecushioning packaging material and that such methods and apparatus have anumber of advantages and characteristics, including those thereinpointed out and others which are inherent in the invention. It isanticipated that variations and modifications to the described form ofapparatus and methods will occur to those skilled in the art and thatsuch modifications and changes may be made without departing from thespirit of the invention or the scope of the appended claims.

We claim:
 1. In an automated apparatus for continuously making foamcushions for packaging purposes, said apparatus including: a cushionforming station whereat a cushion envelope is partially filled with anexpandable cushion foam material as it is formed, means for advancing acontinuous web of envelope-forming material through said cushion formingstation, foam dispenser means adjacent the cushion forming station fordispensing predetermined amounts of an expandable custion foam materialinto a cushion envelope as it is being formed, sealing means at saidcushion-forming station for forming first, second and side seams in theadvancing web to define the cushion envelope, the improvementcomprising:said advancing means includes means for advancing afolder-over web of envelope-forming material including a longitudinallyextending folded side, an opposed open side and a pair of opposing webfaces, said foam dispenser means extending into the open side of saidweb, and said sealing means includes means for continuously,successively forming a labyrinth from a plurality of side seams lyingalong the open side of said web, each said side seam including anelongate seal passsage defined by a pluality of spaced apart, heatsealed bands joining portions of the opposing web faces adjacent theopen side, each of said passages having a length and a cross-sectionalconfiguration defined such that gases are permitted to pass outwardlyfrom the cushion envelope but said expanding and solidifying cushionfoam material is prevented from passing fully through said passages andthereby leaking from the open side of the web.
 2. An apparatus as inclaim 1, wherein said advancing means advances the web downwardlythrough the cushion forming station.
 3. An apparatus as in claim 1,wherein said sealing means for continuously forming said intermittentlabyrinth side seam comprises: at least one roller for contacing theopen side of said web, said roller including an outer surface withheatable regions thereon for forming intermittent heat seals alongportions of the open side of the web which are contacted by said heatedregions, means for heating said heated regions on said roller to heatsealing temperature, and drive means for turning said roller against theopen side of said web during travel of the web through the cushionforming station.
 4. An apparatus as in claim 3, wherein the heatableregions on said roller are provided by an electrically-conductiveresistance tape.
 5. An apparatus as in claim 1, wherein the sealingmeans for forming the first and second seams in the web to define thecushion envelope comprises a pair of opposed and aligned reciprocatingbars, each bar including a web contact face adjacent a web face andextending generally perpendicularly to said folded side, said bars beingactuatable between an open retracted position and a closed extendedposition wherein the web contact faces of said bars are in grippingopposing contact with the faces of the web, one said web contacting faceincluding forwardly projecting spaced apart first and second heat sealsurfaces and a heat seal wire disposed between said first and secondheat seal surfaces and projecting forwardly thereof, means for heatingthe heat seal wire and the first and second heat seal surfaces to heatsealing temperature, and actuator means for reciprocally moving saidbars between their open and closed positions, whereby, actuation of thebars to their closed position in said cushion-forming stationsimultaneously permits the first heat seal surface to form a trailingseal in a first envelope, the second heat seal surface to form a leadingseal in a second envelope being formed and the heat seal wire to form aline of weakness between the first envelope and the second envelope tofacilitate separation of the first and second envelopes from each other.6. An apparatus as in claim 1, further comprising web guide meansdisposed adjacent said cushion forming station for positioning the webin said cushion forming station.
 7. An apparatus as in claim 6, whereinsaid web guide means include: an adjustably positionable horizontal armincluding an end portion with a curved downwardly projecting fingerextending therefrom, said finger including a web-engaging surface forslidably engaging an inner surface of the folded side of the web.
 8. Inan automated apparatus for continuously making foam cushions forpackaging purposes, said apparatus including: a cushion forming stationwhereat a cushion envelope is partially filled with an expandablecushion foam material as it is being formed, means for advancing acontinuous web of envelope-forming material through said cushion formingstation, foam dispenser means adjacent the cushion forming station fordispensing predetermined amounts of an expandable cushion foam materialinto a cushion envelope as it is being formed, sealing means at saidcushion-forming station for forming first, second and side seams in theadvancing web to define the cushion envelope, the improvementcomprising:said advancing means includes means for advancing afolded-over web of envelope-forming material including a longitudinallyextending folded side, an opposed open side and a pair of opposing webfaces, said foam dispenser means extending into the open side web andsaid sealing means including means for continuously forming anintermittent labyrinth side seam along the open side of said web, saidlabyrinth side seam forming means including: a roller assembly includingan outer cylindrical sleeve conductor having a sleeve portion with anouter surface and a projecting radial flange portion extending from oneend of the sleeve portion, an inner cylindrical core conductor having acylindrical portion and a projecting radial flange portion extendingfrom one end of the cylindrical portion, the cylindrical portion of thecore conductor telescopically received within the sleeve portion of theouter sleeve conductor so that their respective flange portions extendin adjacent spaced apart parallel relation, an inner insulative layerdisposed between the cylindrical conductor portion and the sleevecondutor portion, an outer insulative layer surrounding the outersurface of the sleeve portion, a length of electrically conductiveresistance tape disposed on said outer insulative layer, said tapeforming a heatable region on said roller assembly for impartinglabyrinth intermittent heat seals along the open side of said web oncontact therewith, said tape being electrically connected at one end tothe flange portion of the sleeve conductor and electrically connected atthe opposed end to a first end of a pin conductor, said pin conductorextending through the sleeve portion of the sleeve conductor and beingelectrically insulated therefrom, said pin conductor being electricallyconnected at its second opposed end to the cylinder portion of said coreconductor, drive means for turning said roller assembly against saidopen side during travel of the web through the cushion-forming station,and current supply means for heating said tape to sealing temperatureincluding a pair of contacts in electrically conductive relation to theflange portion of the core conductor and the sleeve conductor,respectively.
 9. An apparatus as in claim 8, wherein said tape isapplied in a helical manner on said outer insulative layer to form aseries of upwardly directed diagonal heat seal bands along the open sideof said web.
 10. In an automated apparatus for continuously making foamcushions for packaging purposes, said apparatus including: a cushionforming station whereat a cushion envelope is partially filled with anexpandable cushion foam material as it is formed, means for advancing acontinuous web of envelope-forming material through said cushion formingstation, foam dispenser means adjacent the cushion forming station fordispensing predetermined amounts of an expandable cushion foam materialinto a cushion envelope as it is being formed, sealing means at saidcushion-forming station for forming first, second and side seams in theadvancing web to define the cushion envelope, the improvementcomprising: said advancing means including means for advancing a foldedover web of envelope forming material having a longitudinally extendingfolded side and an opposed open side and a pair of opposing web faces,said foam dispenser means extending into the open side of said web, saidsealing means including means for continuously forming an intermittentlabyrinth side seam along the open side of said web, and a nozzlerinsing apparatus mounted adjacent the foam dispensing means.
 11. Anapparatus as in claim 10, wherein said nozzle rinsing apparatus includesa supply of solvent operatively connected with a pneumatic accumulatorfor directing a short burst of solvent across the face of a nozzle onthe foam dispenser means such that residual materials on the nozzleafter foam is dispensed therefrom may be dislodged and blown toward thefolded side of the envelope being formed and remain in the interior ofthe cusion envelope.
 12. A method for making a foam cushion forpackaging purposes including a cushion envelope partially filled with acushion foam material, said method comprising: providing a length ofenvelope-forming web material, folding said web upon itself in alengthwise direction to define a longitudinally extending folded side,an opposed open side and a pair of spaced opposed web faces,heat-sealing the web faces together to define a first seal extendinggenerally perpendicularly between the folded side and the open side ofthe web, intermittently heat sealing the opposed web faces togetheradjacent the open side of the web to form a labyrinth side seam of agiven first length, thereby defining a foam-receiving pocket, dispensinga predetermined quantity of an expandable cushion foam material into thefoam-receiving pocket, continuing the intermittent heat sealing of thelabyrinth side seam for a second length; and thereafter, heat sealingthe web faces together to define a second seam extending generallyparallel to the first seam between the folded side and the second lengthof said labyrinth side seam.
 13. An automated method for making acontinuous supply of foam cushions for packaging purposes, said methodcomprising: (a) providing a cushion forming station whereat a cushionenvelope is formed as it is partially filled with an expandable cushionfoam material; (b) providing a continuous supply of an envelope-formingweb material fed in one direction through said cushion forming station,said web being folded over itself to provide a longitudinally extendingfolded side, an opposed open side and a pair of opposed spaced-apart webfaces; (c) providing a foam dispenser upstream and adjacent to thecushion forming station, said foam dispenser extending into the openside of the web; (d) continuously heat sealing the opposed web facesadjacent the open side of the web to form an intermittent labyrinth sideseam opposite the folded side as the web passes into the cushion-formingstation; (e) heat sealing the opposed major faces of the web at thecushion forming station to define a downstream second seam, a spacedupstream first seam and an intermediate line of weakness therebetween,said first seam, second seam and line of weakness each extendinggenerally parallel to each other and generally perpendicularly betweenthe folded side and the labyrinth side seam; (f) advancing the web afirst distance through the cushion forming station to define a foamreceiving pocket in said web extending on the downstream side of thecushion forming station; (g) dispensing a predetermined quantity ofexpandable cushion foam material from the dispenser into said pocket;(h) advancing the web a second distance through the cushion formingstation to provide a predetermined cushion length and (i) thereafter,repeating steps (e)-(h) to provide a continuous supply of foam cushionsseparable from each other along the lines of weakness.
 14. An automatedapparatus for continuously making foam cushions for packaging purposes,said apparatus comprising: a cushion forming station whereat a cushionenvelope is partially filled with an expandable cushion foam material asit is formed, means for advancing a continuous folded over web ofenvelope forming material having a longitudinally extending folded side,an opposed open side and a pair of opposing web faces through saidcushion forming station in one direction, foam dispenser means adjacentthe cushion forming station extending into the open side of said webbetween said web faces for dispensing predetermined amounts of anexpandable cushion foam material into a cushion envelope as it is beingformed, and sealing means at the cushion forming station including meansfor forming a leading seam and a trailing seam and means forcontinuously forming an intermittent labyrinth side seam along the openside in the advancing web to define the cushion envelope.
 15. In anautomated apparatus for continuously making foam cushions for packagingpurposes, said apparatus including: a cushion forming station whereat acushion envelope is partially filled with an expandable cushion foammaterial as it is formed, means for advancing a continuous web ofenvelope-forming material through said cushion forming station, foamdispenser means adjacent the cushion forming station for dispensingpredetermined amounts of an expandable cushion foam material into acushion envelope as it is being formed, sealing means at said cushionforming station for forming first, second and side seams in theadvancing web to define the cushion envelope, the improvementcomprising: said advancing means including means for advancing afolded-over web of envelope-forming material having a longitudinallyextending folded side, an opposed open side and a pair of opposing webfaces, said foam dispenser means extending into the open side of saidweb, and said sealing means including means for continuously,successively forming a labyrinth from a plurality of side seams lyingalong the open side of said web, each said side seam including a sealpassage defined by a plurality of spaced apart heat sealed bands joiningportions of the opposing web faces adjacent the open side, each of saidpassages being angled with respect to the open side of the web andhaving a length and a cross sectional configuration defined such thatgases are permitted to pass outwardly from the cushion envelope but saidexpanding and solidifying cushion foam material is prevented frompassing fully through said passages and thereby leaking from the openside of the web.